The invention relates to an automatic transmission in motor vehicles according to the preamble of Claims 1 and 2.
German Patent Document DE 196 25 019 A1, for example, is based on such an automatic transmission. From that document, an electric driving position selecting element is known in the form of a selector lever which can be moved along the directions of a rectangular system of axes. The selector lever is equipped with electric shifting elements by means of which the respective selected driving position, such as B, P, R, N and D, is transmitted as an electric signal to the electronic transmission control unit. Corresponding to the selected driving position, the transmission control unit controls the required hydraulic and/or mechanical actuators in order to engage the selected driving position. The electric driving position selecting element can be independent of the transmission mechanism and of the hydraulic system of the transmission and only be electrically connected with the transmission control unit.
It is an object of the invention to warn the driver in the event of a failure of the electrical components in a differentiated manner but only if absolutely necessary.
This object is achieved by means of the characteristics of Claims 1 and/or 2. Advantageous further development of the invention are the objects of the subclaims.
According to the invention, in the event of a failure of the transmission control unit, particularly during the drive, such that a shifting operation can no longer be carried out, when the driving position selecting element is operated in the sense of a driving position change, a corresponding optical, acoustic and/or haptic feedback, which indicates this failure, is emitted to the driver if the driving positions which can be set by means of the driving position selecting elements can still be detected.
In addition or as an alternative, in the event of a failure of the driving position selecting element such that the driving positions, which can be set by the driving position selecting elements, can no longer be detected, a corresponding optical, acoustic and/or haptic feedback is immediately emitted to the driver which indicates this failure.
The optical, acoustic and/or haptic feedback in the event of a failure preferably takes place by an optical, acoustic and/or haptic reaction in the vehicle which is opposite to the optical, acoustic and/or haptic reaction when there is no failure.
In the event of a failure, the optical feedback may also be a differentiated fault report or instructions to carry out actions.
In an advantageous further development, the optical feedback in the event of a failure is the absence of a display which is emitted in the faultless case during each successful operation of the driving position selecting element. Such a display may, for example, in the faultless event, be the display of the selected driving positions or a flashing light which flashes during each successful operation of the driving position selecting element.
The acoustic feedback in the event of a failure is preferably the absence of an acknowledgment sound emitted in the faultless case during each successful operation of the driving position selecting element.
The haptic feedback in the event of a failure is preferably a detectable increase or decrease of the operating force required for the operation of the driving position selecting element.
In addition, when the vehicle is stopped, a repeated feedback can be emitted to the driver in order to remind him again of the failure. The stoppage of the vehicle can be detected by way of the signal of the driving speed v which exists in the vehicle anyhow. Likewise, when the vehicle is stopped or at a driving speed v of 0 km/h, the continued driving can be prevented. For this purpose, the engine is, for example, automatically switched off, the parking brake is automatically applied or the parking position is automatically engaged.